We have blocked drains at the rear of our property. We have three inspection covers and there is water and sewage seaping from under the covers. It started recently during this period of sustained heavy rain. We have had Drainsaid out on 2 occasions; firstly with the normal jetters and then with a larger tanker but they were unable to clear the blockage. We have contacted Welsh Water who say that it is a private matter although the Council have told us there is an adopted sewer next to the property. Any ideas what action I should take next with the problem to get the blockage cleared.